For the past many years the freight industry has used a hand brake to restrain the movement of a rail car when the car is parked and not connected to a locomotive. Such brakes are applied and released manually by brakeman or other rail car service personnel. Since rail cars commonly weigh as much as 150 tons, such hand brakes must apply through the braking system a large force between the brake shoes and the wheels of the car. Typical hand brake systems are shown in the 1997 issue of Car and Locomotive Cyclopedia, in Section 8 entitled xe2x80x9cFreight Car Brakesxe2x80x9d which is incorporated herein by reference.
Heretofore, typical hand brakes included a hand wheel which is grasped by the rail car service personnel and rotated to cause the chain connected to the braking system of the car to be wound about a chain wheel in actuating the braking system. The force needed to be applied to the hand wheel in order to properly set the brake system is normally between 100 and 200 pounds. This would be an excessive required turning force should the rail industry desire that the braking operation be gender neutral. Also, the rail car service personnel or brakeman must climb onto the rail car to operate the hand brake, which is less safe than if the brake could be operated from a ground position. Further, the applied necessary brake force varies greatly so that one is never certain whether a sufficient amount of force has been applied to the braking system to actually hold the car or whether too great of a force may have been applied which could cause damage to the connected air brake system. Also there is no indicator which informs the rail car service personnel that the brake has been applied or is not applied thus making it difficult to determine whether the hand brake has been properly applied on parked cars or released when the cars are readied for movement.
In the subject invention, the hand wheel is replaced by a hydraulic cylinder which is connected by gearing to the chain wheel. The hydraulic cylinder which in the preferred embodiment is actuated by a handle causes rotation of the chain wheel which in turn causes the wrapped actuator chain to be drawn in order to actuate the braking system. A securement device which is releasable and which is preferably of a pawl and ratchet construction is provided to secure the chain wheel against rotative movement even if hydraulic pressure is reduced when the desired braking force has been applied by the actuator chain to the braking system. An indicator is also provided which serves as a visual indication of whether the hand brake is set or released.
Accordingly, it is an object of this invention to provide a hand brake which is for a rail car and which is of simplified and reliable operation.
Another object of this invention is to provide a hand brake which is for a rail car and which may be actuated with minimal manual force.
Another object of this invention is to provide a braking system which is for a rail car and which includes a hand brake having an indicator to indicate whether the brake has been appropriately applied or is in a released or unapplied position.
Still another object of this invention is to provide a hand brake which is for a rail car and which utilizes hydraulic actuation through a hydraulic cylinder having a preset high pressure limit so as to adapt the hand brake for multiple classes of hand brake operation.
And still another object is to protect the brake system from excessive applied hand brake force.
A further object is to control the hand brake release force rate.
A still further object is to connect the inactive side of the hydraulic cylinder to the reservoir or tank to provide erosion and seal protection for the cylinder.
Other objects of this invention will become apparent upon a reading of the following description.